Nokea
Which of the following statements is FALSE regarding B cells?
- A. B cells that recognize high concentrations of antigen (self) in the absence of other signals undergo apoptosis in the bone marrow
- B. Bone marrow stem cells migrate to the thymus and develop into B cells
- C. B cells synthesize antibodies and put them on their cell surface
- D. B cells can undergo class switching and produce a different antibody type
Correct Answer: B
Rationale: B cells develop in the bone marrow, not the thymus. Firstly, hematopoietic stem cells in the bone marrow give rise to B cells. They undergo maturation and selection processes in the bone marrow, not in the thymus. Therefore, choice B is false. On the other hand, choices A, C, and D are correct. A is true because B cells with high affinity to self-antigens undergo apoptosis to prevent autoimmunity. C is true since B cells synthesize antibodies which can be displayed on their surface as B cell receptors. D is true because B cells can undergo class switching to produce different types of antibodies based on the immune response requirements.
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Congenital CMV infections are caused by:
- A. coronavirus
- B. herpes simplex virus
- C. cytomegalovirus
- D. Epstein-Barr virus
Correct Answer: C
Rationale: The correct answer is C: cytomegalovirus (CMV). Congenital CMV infections are caused by the transmission of CMV from a pregnant woman to her fetus. CMV is a type of herpes virus, not a coronavirus (A), herpes simplex virus (B), or Epstein-Barr virus (D). CMV is known to cause serious health issues in newborns, making it crucial to identify and manage during pregnancy.
In order to prevent wound infection associated with surgical procedures a patient was given a synthetic antiprotozoan drug with a high activity against Helicobacter pylori. Specify this drug:
- A. Metronidazole
- B. Doxycycline hydrochloride
- C. Chingamin
- D. Acyclovir
Correct Answer: A
Rationale: The correct answer is A: Metronidazole. Metronidazole is a synthetic antiprotozoan drug with high activity against Helicobacter pylori, a bacterium that can cause wound infections. Metronidazole specifically targets anaerobic bacteria like H. pylori, making it effective in preventing wound infections.
Incorrect choices:
B: Doxycycline hydrochloride - Doxycycline is primarily used for bacterial infections, not protozoan infections like H. pylori.
C: Chingamin - Chingamin is not a commonly used drug for treating H. pylori infections or preventing wound infections.
D: Acyclovir - Acyclovir is an antiviral drug used to treat herpes infections, not bacterial or protozoan infections like H. pylori.
The correct hierarchical order for virus classification is
- A. order, genus, family, subfamily, species.
- B. species, genus, family, subfamily, order.
- C. order, family, subfamily, genus, species.
- D. genus, order, family, subfamily, species.
Correct Answer: C
Rationale: The correct hierarchical order for virus classification is order, family, subfamily, genus, species. This is because classification starts at a broader level (order) and narrows down to a more specific level (species). Order comes first to group viruses based on common characteristics, followed by family, which further categorizes them. Subfamily refines the classification, then genus groups similar viruses together, and species distinguishes different strains within a genus. Choice A is incorrect because it places genus before family, which is not the correct sequence. Choice B is incorrect as it starts with species, which is the most specific level. Choice D is incorrect because it places genus at the beginning, which is too specific for the hierarchical order.
A pregnant woman applied to a doctor with complaints typical for toxoplasmosis. The doctor took a sample of her blood. What serological tests should be performed in this case?
- A. Complement binding assay
- B. Precipitation test
- C. Neutralization test
- D. Widal's test
Correct Answer: A
Rationale: The correct serological test for diagnosing toxoplasmosis is the Complement Binding Assay (A) because it detects antibodies specific to the Toxoplasma gondii parasite. This test is highly sensitive and specific for toxoplasmosis.
Choice B, Precipitation test, is not used for toxoplasmosis diagnosis but rather for other diseases like syphilis.
Choice C, Neutralization test, is not specific for toxoplasmosis and is used for other types of infections.
Choice D, Widal's test, is used for diagnosing typhoid fever and is not relevant for toxoplasmosis.
In summary, the correct answer (A) is specific to toxoplasmosis, while the other choices are used for different diseases and are not suitable for diagnosing toxoplasmosis.
A patient who has been taking tetracycline for a long time has developed candidosis of mucous membranes. What drug shoul administered for its treatment?
- A. Itraconazole
- B. Griseofulvin
- C. Nitrofungin
- D. Amphotericin
Correct Answer: A
Rationale: The correct answer is A: Itraconazole. Itraconazole is an antifungal medication commonly used to treat candidosis. It works by inhibiting the synthesis of ergosterol, a key component of fungal cell membranes. This action disrupts the integrity of the fungal cell membrane, leading to cell death. Griseofulvin (B) is primarily used to treat fungal infections of the skin and nails, not mucous membranes. Nitrofungin (C) is not commonly used for candidosis treatment. Amphotericin (D) is a potent antifungal medication but is typically reserved for severe or systemic fungal infections due to its potential side effects.